The force atlas for assembly operations I

Project No. BGIA 4141

Status:

completed 07/2008

Aims:

The maximum static action forces for humans that are stated in standards and in the literature relate solely to exertion in a body posture close to upright. Industrial manufacturing processes however frequently require physical forces to be exerted in a non-upright posture, with the joints outside their neutral positions.

The project, which was sponsored by the Federation of Institutions for Statutory Accident Insurance and Prevention (HVBG) (FFFP0262 "Force Atlas for Assembly Operations - Part II"), therefore had the objective of measuring action forces of the whole body and of the hand-arm system as percentiles for typical real-case postures and applications in the operations of industrial partners to the project and in the laboratory, and of listing them in the "force atlas for assembly operations". The maximum static action forces were to be used to define maximum recommended "bearable" force values in consideration of personal and task-specific parameters. For this purpose, a suitable method was to be developed, in consideration of correction factors, which could also be used in the context of risk assessments. Besides the statistical analysis of the force data, the results were to be converted for presentation in the form of a force atlas. The final task was that of developing an assessment method for the definition of maximum recommended action forces from the maximum forces in the force atlas.

The force atlas was intended for use during the planning of industrial workplaces and during risk assessments.

Activities/Methods:

At the BGIA - Institute for Occupational Safety and Health, two mobile and modular measurement systems were developed further and fabricated. The systems employ two three-component measurement handles for the measurement of whole-body forces and hand-arm forces. In order for the measured values to be recorded, the software of the CUELA measurement system was adapted to the specific measurement application and an interface created for transmission of data to an external software application.

Besides the field measurements conducted in the plants involved in the project, whole-body force measurements (three-dimensional movement measurements) in typical body postures for assembly tasks were also conducted in the laboratory for validation purposes.

Results:

The "force atlas for assembly operations" shows the maximum isometric force values as percentiles under typical real-case conditions for 54 force exertions performed with both hands of the whole-body system, and for 38 force exertions of the hand-finger system. By means of correction factors, which were determined in the laboratory studies, the maximum forces can be determined for asymmetrical and one-handed force exertions. Based upon this data, an evaluation method was developed for determining the maximum recommended force values in consideration of personal and task-specific parameters which is suitable for use in both planning analyses and analyses of existing situations.